JP2000067887A - Solid polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light and compact solid polymer fuel cell. SOLUTION: This polymer electrolyte fuel cell is formed by laminating plural number of cells each of which is equipped with a solid polymer electrolyte film, a pair of electrodes having a catalytic reaction layer placed so as to sandwich the solid polymer electrolyte film and a means for supplying and distributing fuel, containing hydrogen, to one surface of the electrode and for supplying and distributing oxidizer gas, containing oxygen, to another surface of the electrodes, through a conductive separator, and is equipped with an end plate to press down both end surface of the cell laminated, a linking member 104 to fasten the end plate and an auxiliary plate 107 having a blade spring to apply a fastening force to the linking member 104 and the end plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a portable power supply,
The present invention relates to a room temperature operation type polymer electrolyte fuel cell used for an electric vehicle power supply, a home cogeneration system, and the like.

[0002]

2. Description of the Related Art In a polymer electrolyte fuel cell, a fuel gas such as hydrogen and an oxidant gas such as air are electrochemically reacted by a gas diffusion electrode, and simultaneously generates electricity and heat. FIG. 6 shows an example of a polymer electrolyte fuel cell.
Shown in On both surfaces of the polymer electrolyte membrane 3 for selectively transporting hydrogen ions, a catalytic reaction layer 2 mainly composed of a carbon powder carrying a platinum-based metal catalyst is closely arranged. Further, a pair of diffusion layers 1 having both gas permeability and conductivity are arranged in close contact with the outer surface of the catalyst reaction layer 2. The diffusion layer 1 and the catalytic reaction layer 2 form an electrode 9.

On the outside of the electrode 9, an electrode electrolyte assembly (hereinafter referred to as MEA) 10 of the electrode 9 and the polymer electrolyte 3 is mechanically fixed, and an adjacent MEA is fixed.
A conductive separator plate 4 for electrically connecting the units 10 in series with each other is provided. A gas passage 5 for supplying a fuel gas and an oxidizing gas to the electrode 9 and carrying away a gas generated by the reaction and an excess gas is formed in a portion of the separator plate 4 which is in contact with the electrode 9. Further, on the other surface of the separator plate 4, a cooling flow path 24 for circulating cooling water for keeping the battery temperature constant is provided. By circulating the cooling water in this way, the heat energy generated by the reaction is used in the form of hot water or the like. In order to prevent hydrogen and air from leaking out of the battery and mixing with each other, and to prevent cooling water from leaking out of the battery, a sealing material 17 and an O-ring 18 Is arranged. As another sealing method, as shown in FIG. 7, a gasket 19 having the same thickness as the electrode 9 and made of a resin or a metal plate is arranged around the electrode, and the gasket 19 and the separator plate are arranged. There is also a structure in which the gap with the seal 4 is sealed with grease or an adhesive. Further, in recent years, the MEA 10 using the electrode 9 having the same size as the polymer electrolyte membrane 3 has been used, and as shown in FIG. A method has been proposed in which a gas seal between the electrode 9 and the separator plate 4 is secured by using a solidified material.

[0004] Many fuel cells have a stacked structure in which a number of cells are stacked. In the case of a fuel cell, a cooling plate is provided for every one or two cells of a unit cell in order to discharge heat generated together with electric power to the outside of the cell. Generally, the cooling plate has a structure in which a heat medium such as cooling water flows through a thin metal plate. Further, as shown in FIGS. 6 to 8, a flow path is formed on the back surface of the separator plate 4 constituting the unit cell, that is, the surface on which the cooling water is desired to flow, and the separator plate 4 is formed.
There is also a method of making itself function as a cooling plate. At that time, an O-ring or gasket is also required to seal the heat medium such as cooling water, but this seal must completely crush the O-ring to ensure sufficient conductivity between the upper and lower cooling plates. There is.

[0005] In such a laminated battery, there is generally used an internal manifold type in which a gas supply hole and a gas discharge hole for each cell called a manifold and a supply and discharge hole of cooling water are required to be secured inside the laminated battery. It is. However, when the battery is operated using the reformed actual gas, the CO concentration increases in the downstream region of the fuel gas flow path of each battery, and as a result, the temperature decreases due to electrode poisoning, and the decrease in temperature further promotes electrode poisoning. Will be. In order to alleviate such a battery performance reduction phenomenon, an external manifold type has been reviewed as a structure in which a frontage of a gas supply / discharge unit from the manifold to each unit cell can be made as wide as possible. In any case, it is necessary to stack a large number of unit cells including the cooling unit in one direction, arrange end plates on both end surfaces thereof, and fix the pair of end plates between the pair of end plates with a fastening rod. As a fastening method, it is desirable to fasten the unit cells as uniformly as possible in the plane, and a metal material such as stainless steel is usually used for the end plate and the fastening rod from the viewpoint of mechanical strength. These end plates and fastening rods and the laminated battery are electrically insulated by an insulating plate or the like, and have a structure in which current does not leak outside through the end plates. As for the fastening rod, an improved system has been proposed in which the fastening rod is passed through a through hole formed in the separator plate, or the entire lamination pond is fastened with a metal belt over the end plate.

Further, in any of the sealing methods shown in FIGS. 6 to 8, a constant tightening pressure is required in order to maintain the sealing property, and a screw spring or a disc spring is inserted between the fastening rod and the end plate. It has a configuration. Further, the tightening pressure secures electrical contact between members constituting the battery, such as a separator, an electrode, and an electrolyte membrane. In the method of disposing a sealing material or an O-ring around the electrodes, a considerable surface pressure is required for sealing gas such as hydrogen gas or air. Therefore, a structure is employed in which the sealing effect is maintained by sandwiching the sealing material and the sealing portion between separator plates disposed above and below the sealing material. According to this method, a relatively large tightening force must be constantly applied, so that a tightening mechanism such as an end plate or a tightening rod becomes long, causing an increase in the weight of the entire fuel cell. In addition, when pressure is applied to the seal portion or the electrode portion for a long period of time, the components are distorted. As a result, the surface pressure required for the seal and the electrode is reduced, so that a mechanism for absorbing the strain is required for the tightening mechanism. Therefore, conventionally, a spring has been installed at the end of the tightening rod and tightened. However, such a method has caused an increase in the size of the mechanism.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a solid oxide fuel cell having a small and simple structure for fastening a stacked battery. It is another object of the present invention to provide a solid oxide fuel cell which has a fastening mechanism for a stacked battery capable of suppressing creep deformation due to prolonged pressurization and has excellent long-term stability.

[0008]

The polymer electrolyte fuel cell according to the present invention is a stacked battery comprising a plurality of unit cells, each of which is composed of a battery component such as an electrolyte membrane, an electrode having a catalytic reaction layer, and a separator. The stacked battery is fastened with a connecting member for connecting the end plates, which hold the both ends, and an auxiliary plate having a leaf spring function for applying a fastening force to the end plate and the connecting member.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A polymer electrolyte fuel cell according to the present invention comprises a solid polymer electrolyte membrane, a pair of electrodes having a catalytic reaction layer interposed between the solid polymer electrolyte membranes, and one of the electrodes. Means for supplying and distributing a fuel containing hydrogen and for supplying and distributing an oxidizing gas containing oxygen to the other surface of the electrode. The fuel cell includes an end plate that presses both end surfaces of the stacked unit cells, a connecting member that fastens the end plate, and an auxiliary plate that has a leaf spring function of providing a fastening force to the connecting member and the end plate. . Another polymer electrolyte fuel cell according to the present invention includes a solid polymer electrolyte membrane, a pair of electrodes having a catalytic reaction layer disposed with the solid polymer electrolyte membrane interposed therebetween, and a fuel containing hydrogen in one of the electrodes. And a means for supplying and distributing an oxidizing gas containing oxygen to the other surface of the electrode, and a unit cell comprising a plurality of stacked unit batteries via a conductive separator. An end plate comprising a leaf spring for holding both end surfaces of the stacked unit batteries is provided, and a connecting member for fastening the end plate is provided. At this time,
Only one side of the end plate used for fastening may be made of a member having a leaf spring function.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings.

Example 1 A carbon powder having a particle diameter of several microns or less was immersed in an aqueous solution of chloroplatinic acid, and a platinum catalyst was supported on the surface of the carbon powder by a reduction treatment. At this time, the weight ratio of carbon to the supported platinum was 1: 1. Next, the carbon powder supporting platinum was dispersed in an alcohol solution of a polymer electrolyte to prepare a slurry.
On the other hand, carbon paper having a thickness of 400 μm to be an electrode is impregnated with an aqueous dispersion of fluororesin (“Neoflon ND-1” manufactured by Daikin Industries, Ltd.), dried, and then heat-treated at 400 ° C. for 30 minutes. Water repellency was imparted to this carbon powder. The slurry containing the obtained carbon powder was uniformly applied to one surface of the carbon paper subjected to the water-repellent treatment to form the catalytic reaction layer 2 shown in FIG. A pair of carbon papers provided with the catalytic reaction layer 2 face each other with the surface provided with the catalytic reaction layer 2 facing inward, and are overlapped with the polymer electrolyte membrane 3 interposed therebetween. Body (hereinafter referred to as MEA) 1
0 was obtained. The MEA 10 was sandwiched between both sides of the separator plate 4 made of airtight carbon to assemble a unit cell.

The separator plate 4 has a thickness of 4 mm, and a gas passage 5 having a width of 2 mm and a depth of 1 mm is formed on the surface thereof by cutting, and a gas manifold hole 6 and a cooling gas hole 6 are formed around the gas passage 5. A water manifold hole 7 is provided. When the MEA 10 is sandwiched between the separators, EPDM is provided around the electrodes 9 on both sides of a polyethylene terephthalate (PET) sheet having the same outer dimensions as the carbon separator.
A gasket 8 with a sheet attached was arranged. After two such cells are stacked, a cooling channel 24 through which cooling water flows is provided.
Were laminated to obtain a battery constituent unit. Note that an O-ring was not used for sealing the cooling channel 24 as in a conventional fuel cell.

A polymer fuel cell as shown in FIGS. 2 and 3 was assembled by using the above-mentioned cell structural units. The output of the stacked battery 106 is supplied from a pair of output terminals 108 to an external device (not shown). Fuel gas supply port 109
The oxidizing gas supply port 110 communicates with a fuel cell supply manifold (not shown) and an oxidizing gas supply manifold (not shown) of the stacked battery, respectively. Gas generated by the reaction and unreacted gas are discharged from the fuel gas outlet 112 and the oxidizing gas outlet 113 to the outside of the battery. Further, the cooling water supplied to the battery from the cooling water supply port 111 passes through the inside of the battery, and is then discharged outside the battery from the cooling water discharge port 114.

First, a metal current collector 100 and an insulating plate 101 were sequentially stacked on both end surfaces of a stacked battery 106 formed by stacking 50 battery constituent units. Further, end plates 102 and 103 were superimposed on both end surfaces of the laminate, respectively. Then, on the upper surface of the end plate 102,
An auxiliary plate 107 made of spring steel was provided. The plate-shaped connecting member 104 has hooks 104a and 104b on a pair of side edges. The hooks 104a and 104b of the connecting member 104 are engaged with the concave portion 107a provided on the peripheral portion of the outer surface of the auxiliary plate 107 and the concave portion 103a provided on the peripheral portion of the outer surface of the end plate 103, respectively. The male screw 105 was screwed into the female screw part 107b, and the laminated battery 106 was fixed by pressing the tip thereof. Thereby, the auxiliary plate 107 functions as a leaf spring. That is, when the male screw 105 mounted on the auxiliary plate 107 presses the end plate 102, the connecting member 104 connected to the auxiliary plate 107 is pressed.
The fastening force works. At this time, a distortion corresponding to the fastening force is generated between the female screw portion 107b and the concave portion 107a of the auxiliary plate 107. This distortion makes it possible to maintain the generated fastening force. Fastened laminated battery 10
No. 6 undergoes creep deformation over time due to its material properties. However, such creep deformation can be absorbed by the plate spring function of the auxiliary plate 107, and a stable fastening force can be constantly applied to the stacked battery 106. become.

Example 2 A polymer fuel cell shown in FIGS. 4 and 5 was assembled using the same cell structural units as used in Example 1. A current collector plate 100 and an insulating plate 101 made of metal were sequentially stacked on both end surfaces of a stacked battery 106 formed by stacking 50 battery constituent units. Further, end plates 120 are respectively provided on both end surfaces of the laminate.
And 121 were superimposed. Next, a bolt 122 was passed through a through hole formed at a position facing each of the end plates 120 and 121, and a nut 124 was screwed to the tip of the bolt 122 via a spring 123 for absorbing creep deformation.
Thereby, the stacked battery 106 is compressed and fixed in the stacking direction. Here, the end plates 120 and 121 are
At its ends, sleds are provided at both ends in a direction opposite to the surface facing the stacked battery 106, and function as leaf springs. As described above, by fastening the end plates 120 and 121 with the connecting member, the stacked battery 1 sandwiched between the two is connected.
The fastening force acts on 06. Generally, in order to reduce the size of the entire battery, fastening of the end plates is performed at the ends. Then, by providing a warp in advance to the end plates, when the end plates are fastened, a strain corresponding to the fastening force is generated in each of them. Therefore, even when the entire stacked battery is fastened with a necessary fastening force, it is possible to generate a uniform surface pressure on the stacked battery. At this time, the same effect can be obtained even in a configuration in which the amount of warpage is optimized for only one end plate.

[0016]

According to the present invention, the weight of the mechanism for applying the fastening force to the stacked battery can be reduced, so that a lightweight and compact polymer electrolyte fuel cell can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part of a polymer electrolyte fuel cell according to one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the polymer electrolyte fuel cell.

3A and 3B are views showing the appearance of the polymer electrolyte fuel cell, wherein FIG. 3A is a plan view and FIG. 3B is a side view.

FIG. 4 is a front view of a polymer electrolyte fuel cell according to another embodiment of the present invention.

FIG. 5 is a plan view of the polymer electrolyte fuel cell.

FIG. 6 is a longitudinal sectional view of a main part showing an example of a fluid sealing method in a polymer electrolyte fuel cell.

FIG. 7 is a longitudinal sectional view of a main part showing an example of another fluid sealing method in a polymer electrolyte fuel cell.

FIG. 8 is a longitudinal sectional view of a main part showing an example of still another fluid sealing method in a polymer electrolyte fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diffusion layer 2 Catalytic reaction layer 3 Solid polymer electrolyte membrane 4 Separator plate 5 Gas flow path 6 Gas manifold hole 7 Cooling water manifold hole 8 Gasket 9 Electrode 10 Electrode electrolyte assembly 17 Sealing material 18 O ring 19 Gasket 21 Resin 24 Cooling flow path 100 Current collecting plate 101 Insulating plate 102, 103, 120, 121 End plate 103a Recess 104 Connecting member 104a, 104b Hook 105 Male screw 106 Stacked battery 107 Auxiliary plate 107a Recess 107b Female thread 108 Output terminal 109 Fuel gas Supply port 110 Oxidant gas supply port 111 Cooling water supply port 112 Fuel gas outlet 113 Oxidant gas outlet 114 Cooling water outlets 120a, 121b Through hole 122 Bolt 123 Spring 124 Nut

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuhito Hato, 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Makoto Uchida 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Eiichi Yasumoto 1006 Odaka, Kazuma, Kadoma, Osaka Pref. Yasushi 1006 Kadoma Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Teruhisa Kamihara 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006 Matsushita Electric Industrial Co., Ltd. F term (reference) 5H026 AA06 CC08 CX08

Claims (3)

[Claims] 1. A solid polymer electrolyte membrane, a pair of electrodes having a catalytic reaction layer disposed on both sides of the solid polymer electrolyte membrane, and supplying and distributing a fuel gas containing hydrogen to one of the electrodes; A polymer electrolyte fuel cell in which a plurality of unit cells each having a unit for supplying and distributing an oxidizing gas containing oxygen to the other surface of the electrode are stacked with a conductive separator interposed therebetween. A polymer electrolyte fuel comprising: an end plate for holding both end faces of the unit cell; a connecting member for fastening the end plate; and an auxiliary plate having a leaf spring function for applying a fastening force to the connecting member and the end plate. battery. 2. A solid polymer electrolyte membrane, a pair of electrodes having a catalytic reaction layer disposed on both sides of the solid polymer electrolyte membrane, and a fuel gas containing hydrogen supplied and distributed to one of the electrodes; A unit cell comprising means for supplying and distributing an oxidizing gas containing oxygen to the other surface of the electrode, a polymer electrolyte fuel cell in which a plurality of unit cells are stacked via a conductive separator, A polymer electrolyte fuel cell, comprising: an end plate formed of a leaf spring for pressing both end surfaces of a unit cell; and a connecting member for fastening the end plate. 3. The polymer electrolyte fuel cell according to claim 2, wherein a member having a leaf spring function is used as one of a pair of end plates used for fastening.